Three-pipe multi-split air conditioning system and control method thereof

ABSTRACT

A three-pipe multi-split hot water system, including: an outdoor unit, the outdoor unit including a compressor, an oil separator, a first switching apparatus, a second switching apparatus, a fin heat exchanger, a double-pipe heat exchanger, a compressor heat dissipation module, a plate heat exchanger, a first electronic expansion valve, a second electronic expansion valve, a third electronic expansion valve, and a gas-liquid separator; at least two indoor units, any one of the indoor units including an indoor unit heat exchanger, a fourth electronic expansion valve, and an indoor unit fan; and a hydraulic module, the hydraulic module including a refrigerant-water heat exchanger, a water pump, a water temperature detection sensor, a water flow switch, a solenoid valve, and a fifth electronic expansion valve, where the outdoor unit is connected to any one of the indoor units and to the hydraulic module by a gas pipe and a liquid pipe.

FOREIGN PRIORITY

This application claims priority to Chinese Patent Application No. 202110411109.4, filed Apr. 16, 2021, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference.

TECHNICAL FIELD OF INVENTION

The present invention relates to the field of air conditioning technologies, and in particular, to a three-pipe multi-split hot water system and a method for controlling the same.

BACKGROUND OF THE INVENTION

At present, in a hot water production mode or a heating mode of an air conditioner in an existing multi-split hot water system, in a defrosting process of the system, a hydraulic module or an indoor unit needs to be used as an evaporator to absorb heat. To reduce the impact of the defrosting process on the temperature in an indoor environment and the impact of not turning on the indoor unit, the indoor unit usually enters an anti-cold air mode in the defrosting process. If a fan of the indoor unit is not turned on, a large amount of liquid refrigerant flows through the indoor unit and returns to a compressor. In this process, the compressor is prone to liquid shock, affecting the service life of the compressor and the reliability of the system. When the hydraulic module or the indoor unit is used as the evaporator in the defrosting process, the water temperature in the hydraulic module drops or the use environment temperature on the inner side of the air conditioner drops, affecting user experience. In addition, a four-way valve needs to be reversed in the defrosting process, and heating or hot water production cannot be effectively implemented, reducing the time of effective heating or hot water production of the air conditioner, resulting in low effective utilization of equipment.

During defrosting of a conventional multi-split hot water system, it is necessary to control a four-way valve of an indoor unit or a hydraulic module to be reversed. The shock noise of a refrigerant in a process of reversing the four-way valve of the indoor unit forms high noise on an indoor side. In addition, in an anti-cold air defrosting process of the indoor unit, a large amount of refrigerant still flows through, and as a result, the refrigerant produces a flowing noise, seriously affecting the user experience. The hydraulic module is reversed, a large amount of low-pressure liquid refrigerant flows through the hydraulic module, and the hydraulic module is prone to freezes, causing damage to the hydraulic module.

For the conventional multi-split hot water system, to implement a defrosting function, a solenoid valve in communication with a gas pipe of an air conditioner needs to be added on the side of the hydraulic module. The solenoid valve of the hydraulic module is opened in the defrosting process, and the hydraulic module is used for defrosting, leading to an increased cost of the hydraulic module and complex design of the hydraulic module.

If a phase change heat storage method is used for non-stop defrosting in the conventional multi-split hot water system, although heat can be stored within an idle time and released in the defrosting process, a phase change heat storage module of the system requires a high cost and has a large volume, making it difficult to miniaturize the equipment and reduce costs.

In the conventional multi-split hot water system, if a method for defrosting heat exchangers in turn is used for non-stop defrosting, although some heat exchangers that enter defrosting can be fully defrosted in the defrosting process, a large amount of refrigerant flows within a short period of time into the remaining heat exchangers that perform evaporation and heat absorption, which intensely increases the frosting speed in the heat exchangers. In addition, in a non-stop defrosting form of double heat exchangers, a heat exchanger needs to keep the fan stationary to ensure that heat is gathered and used for defrosting. In comparison, a heat exchanger in an evaporative state needs to keep the fan at the highest gear of wind speed, to slow down frosting in the heat exchanger. This defrosting method involves contradictory control, and it is difficult to reach a balance. When the conventional multi-split hot water system operates at high load, because there is a high-pressure superheated refrigerant at an exhaust port of a compressor and the superheated refrigerant has low heat exchange efficiency, a large heat exchanger area is required to cool the refrigerant, resulting in a relatively large volume of a heat exchanger in an outdoor unit, leading to a high overall cost of air conditioning equipment.

At light load, because the environmental temperature is low, the refrigerant tends to evaporate incompletely on the indoor side, and the incompletely evaporated refrigerant returns to the compressor and tends to cause liquid shock to the system, affecting the reliability of the compressor and the operation reliability of the system.

SUMMARY OF THE INVENTION

The present invention is to at least resolve one of technical problems in the prior art. For this, the present invention provides a three-pipe multi-split hot water system and a method for controlling same, so that the impact of a defrosting process on the temperature in an indoor environment and the water temperature of a hydraulic module can be avoided, thereby improving the reliability of the overall operation of the system, and the reversal noise and the flowing noise of a refrigerant in the defrosting process are also avoided, thereby improving the comfort for a user in a use process.

To achieve the foregoing objective, a first aspect of the present invention provides a three-pipe multi-split hot water system, including:

an outdoor unit, the outdoor unit including a compressor, an oil separator, a first switching apparatus, a second switching apparatus, a fin heat exchanger, a double-pipe heat exchanger, a compressor heat dissipation module, a plate heat exchanger, a first electronic expansion valve, a second electronic expansion valve, a third electronic expansion valve, and a gas-liquid separator;

at least two indoor units, any one of the indoor units including an indoor unit heat exchanger, a fourth electronic expansion valve, and an indoor unit fan; and;

a hydraulic module, the hydraulic module including a refrigerant-water heat exchanger, a water pump, a water temperature detection sensor, a water flow switch, a solenoid valve, and a fifth electronic expansion valve,

where the outdoor unit is connected to any one of the indoor units and to the hydraulic module by a gas pipe and a liquid pipe.

In the three-pipe multi-split hot water system according to the embodiments of the present invention, a liquid-side cut-off valve, a gas-side cut-off valve, and a hydraulic module cut-off valve are disposed on the outdoor unit, the liquid-side cut-off valve is connected to a liquid pipe of the indoor unit and a liquid pipe of the hydraulic module, the gas-side cut-off valve is connected to a gas pipe of the indoor unit, and the hydraulic module cut-off valve is connected to a gas pipe of the hydraulic module.

In the three-pipe multi-split hot water system according to the embodiments of the present invention, the first switching apparatus and the second switching apparatus are four-way valves.

In the three-pipe multi-split hot water system according to the embodiments of the present invention, each of the first switching apparatus and the second switching apparatus is provided with an interface A, an interface B, an interface C, and an interface D.

Another aspect of the present invention further provides a method for controlling the three-pipe multi-split hot water system, where the second switching apparatus and the second electronic expansion valve are controlled to enable the system to implement at least one mode of cooling, heating, hot water production, and defrosting.

In the method for controlling the three-pipe multi-split hot water system in the embodiments of the present invention, when both heating and hot water production are required, the second switching apparatus is powered on, the fin heat exchanger operates as an evaporator, and the second electronic expansion valve is closed.

In the method for controlling the three-pipe multi-split hot water system in the embodiments of the present invention, when heating, hot water production, and defrosting are all required, the second switching apparatus is powered off, and the second electronic expansion valve is opened.

In the method for controlling the three-pipe multi-split hot water system in the embodiments of the present invention, when both cooling and hot water production are required, the fin heat exchanger operates as a condenser, and the second electronic expansion valve is closed.

In the method for controlling the three-pipe multi-split hot water system in the embodiments of the present invention, when both cooling and hot water production with improved heat exchange efficiency are required, the second electronic expansion valve is closed.

In the method for controlling the three-pipe multi-split hot water system in the embodiments of the present invention, when both cooling and hot water production with an increased degree of superheat at light load are required, the fin heat exchanger operates as a condenser, and the second electronic expansion valve is opened.

The additional aspects and advantages of the present invention are partially provided in the following description and partially become obvious from the following description or understood through the practice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and/or additional aspects and advantages of the present invention will be apparent and easily comprehensible from the description of the embodiments with reference to the accompanying drawings:

FIG. 1 is a structural diagram of a three-pipe multi-split hot water system according to the present application;

FIG. 2 is a system diagram of a three-pipe multi-split hot water system in a heating+hot water production mode according to the present application;

FIG. 3 is a system diagram of a three-pipe multi-split hot water system in a heating+hot water production+defrosting mode according to the present application;

FIG. 4 is a system diagram of a three-pipe multi-split hot water system in a cooling+hot water production mode according to the present application;

FIG. 5 is a system diagram of a three-pipe multi-split hot water system during cooling and hot water production with improved heat exchange efficiency according to the present application; and;

FIG. 6 is a system diagram of a three-pipe multi-split hot water system during cooling and hot water production with an increased degree of superheat at light load according to the present application.

Reference numerals: 100—three-pipe multi-split hot water system; 1—outdoor unit, 11—compressor, 111—compressor heat dissipation module, 12—oil separator, 13—first switching apparatus, 14—second switching apparatus, 15—fin heat exchanger, 16—double-pipe heat exchanger, 17—plate heat exchanger, 18—gas-liquid separator, 101—first electronic expansion valve, 102—second electronic expansion valve, 103—third electronic expansion valve, 104—liquid-side cut-off valve, 105—gas-side cut-off valve, and 106—hydraulic module cut-off valve; 2—indoor unit, 21—indoor unit heat exchanger, 22—fourth electronic expansion valve, and 23—indoor unit fan; and; 3—hydraulic module, 31—refrigerant-water heat exchanger, 32—water pump, 33—water temperature detection sensor, 34—water flow switch, 35—solenoid valve, and 36—fifth electronic expansion valve.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present invention are described below in detail. Examples of the embodiments are shown in the accompanying drawings. The same or similar numerals represent the same or similar elements or elements having the same or similar functions throughout the specification. The embodiments described below with reference to the accompanying drawings are exemplary, and are only used to explain the present invention but should not be construed as a limitation to the present invention.

Referring to FIG. 1, a three-pipe multi-split hot water system 100 includes: an outdoor unit 1, the outdoor unit 1 including a compressor 11, an oil separator 12, a first switching apparatus 13, a second switching apparatus 14, a fin heat exchanger 15, a double-pipe heat exchanger 16, a compressor heat dissipation module 111, a plate heat exchanger 17, a first electronic expansion valve 101, a second electronic expansion valve 102, a third electronic expansion valve 103, and a gas-liquid separator 18; at least two indoor units 2, any one of the indoor units 2 including an indoor unit heat exchanger 21, a fourth electronic expansion valve 22, and an indoor unit fan 23; and; a hydraulic module 3, the hydraulic module 3 including a refrigerant-water heat exchanger 31, a water pump 32, a water temperature detection sensor 33, a water flow switch 34, a solenoid valve 35, and a fifth electronic expansion valve 36; where the outdoor unit 1 is connected to any one of the indoor units 2 and to the hydraulic module 3 by a gas pipe and a liquid pipe. A controller (not shown) communicates with components of the three-pipe multi-split hot water system 100 to control operation of the three-pipe multi-split hot water system 100, as described herein. The controller may be implemented using a microprocessor-based controller executing instructions to perform the operations described herein.

The characteristics of low flowing loss and efficient heat exchange of the double-pipe heat exchanger 16 are used, so that in a defrosting process, heat generated by the compressor 11 can be used to directly defrost the heat exchanger. In this way, the modes of the hydraulic module 3 and an air conditioning indoor unit are kept unchanged, and switching apparatuses are not reversed, thereby avoiding the impact of the defrosting process on the temperature in an indoor environment and the water temperature in the hydraulic module 3. In addition, a generated liquid refrigerant directly flows back to the compressor 11 without evaporation to cause liquid return in the compressor 11, thereby improving the reliability of the overall operation of the system. The double-pipe heat exchanger 16 is used to perform defrosting, to avoid directly connecting the hydraulic module 3 to a low-pressure side to perform defrosting, thereby facilitating protection of the hydraulic module 3, and simplifying the internal structure of the hydraulic module 3 to reduce the cost of the hydraulic module 3.

In some embodiments, a liquid-side cut-off valve 104, a gas-side cut-off valve 105, and a hydraulic module cut-off valve 106 are disposed on the outdoor unit 1, the liquid-side cut-off valve 104 is connected to a liquid pipe of the indoor unit 2 and a liquid pipe of the hydraulic module 3, the gas-side cut-off valve 105 is connected to a gas pipe of the indoor unit 2, and the hydraulic module cut-off valve 106 is connected to a gas pipe of the hydraulic module 3.

In some embodiments, the second switching apparatus 14 and the second electronic expansion valve 102 are controlled to enable the system to implement at least one mode of cooling, heating, hot water production, and defrosting.

In some embodiments, when both heating and hot water production are required, the second switching apparatus 14 is powered on, the fin heat exchanger 15 operates as an evaporator, and the second electronic expansion valve 102 is closed. During conventional hot water production and air conditioning heating, the second switching apparatus 14 is powered on. In this case, the fin heat exchanger 15 operates as the evaporator, and the second electronic expansion valve 102 is closed. In this case, no refrigerant flows through the double-pipe heat exchanger 16, and the system performs conventional air conditioning heating and hot water production functions.

In some embodiments, when heating, hot water production, and defrosting are all required, the second switching apparatus 14 is powered off, and the second electronic expansion valve 102 is opened. When the fin heat exchanger 15 frosts, the second switching apparatus 14 is powered off. In this case, a high-temperature, high pressure refrigerant flows through the fin heat exchanger 15, and frost on the surface of a heat exchanger absorbs heat, turns into water, and flows away from the surface of the heat exchanger, to implement defrosting of the outdoor unit. In addition, the second electronic expansion valve 102 is opened. The refrigerant is throttled by the second electronic expansion valve 102, flows to the double-pipe heat exchanger 16, absorbs heat of the exhaust of the compressor 11 at the double-pipe heat exchanger 16, and returns to an air return side of the compressor 11. In this defrosting process, heat generated by the compressor 11 is used to perform defrosting, to implement non-stop heating of the air conditioning indoor unit and the hydraulic module 3 in the defrosting process, so that the reliability of defrosting of an air conditioning system is improved, and the use experience of the air conditioning indoor unit and the hydraulic module 3 is further improved.

In some embodiments, when both cooling and hot water production are required, the fin heat exchanger 15 operates as a condenser, and the second electronic expansion valve 102 is closed. When the fin heat exchanger 15 operates as the condenser during normal air conditioning cooling, the second electronic expansion valve 102 is closed, and no refrigerant flows through the double-pipe heat exchanger 16, thereby implementing the normal air conditioning cooling and the heat recovery function for hot water production.

In some embodiments, when both cooling and hot water production with improved heat exchange efficiency are required, the second electronic expansion valve 102 is closed. When the degree of superheat of the exhaust and the temperature at the outlet of the fin heat exchanger 15 are high, the second electronic expansion valve 102 is opened, and the refrigerant flows through the double-pipe heat exchanger 16, to reduce the degree of superheat of the exhaust of the fin heat exchanger 15, so that the refrigerant that enters the fin heat exchanger 15 is as close as possible to a gas-liquid two-phase region. In this way, the heat exchange efficiency of the refrigerant in the fin heat exchanger 15 is improved, and the refrigerant can be better condensed at the fin heat exchanger 15, thereby achieving the objective of using a small heat exchanger for a high-capacity horsepower outdoor unit.

In some embodiments, when both cooling and hot water production with an increased degree of superheat at light load are required, the fin heat exchanger 15 operates as a condenser, and the second electronic expansion valve 102 is opened. When the outdoor unit 1 enters light-load cooling, the outer side environment has a low temperature. When the fin heat exchanger 15 operates as the condenser, the second electronic expansion valve 102 is opened, to reduce an amount of refrigerant that flows through the indoor unit 2 of air conditioning cooling. In this case, a part of the refrigerant flows through the double-pipe heat exchanger 16, evaporates, absorbs heat, and flows back to the compressor 11. In this process, a relatively high-temperature refrigerant discharged by the compressor 11 increases the evaporation temperature on an evaporation side, to improve the degree of superheat of return air and the degree of superheat of exhaust, thereby effectively protecting the compressor 11 and protecting the compressor 11 and the system when the system operates at light load. It should be understood that the double-pipe heat exchanger 16 is used to implement that at light load, a part of refrigerant that is supposed to evaporate on an indoor side to return to an exhaust side, and a heat return function of the double-pipe heat exchanger 16 is used to increase the temperature of the return air and the degree of superheat of the return air, thereby ensuring the operation reliability of the compressor 11 and the three-pipe multi-split hot water system 100.

In the description of the present invention, it needs to be understood that orientation or location relationships indicated by terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “up”, “down”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, and “circumferential” are based on orientation or location relationships shown in the accompanying drawings, and are only used to facilitate description of the present invention and simplify description, but are not used to indicate or imply that the apparatuses or elements must have specific orientations or are constructed and operated by using specific orientations, and therefore, cannot be understood as a limit to the present invention. In addition, features defined by “first” and “second” may explicitly or implicitly include one or more features. In the present invention, “a plurality of” herein means “two or more” unless otherwise described.

In the description of the present invention, it needs to be noted that unless otherwise expressly specified and defined, “mounted”, “connected”, and “connection”, should be understood in a broad sense, for example, fixedly connected, detachably connected or integrally connected; or mechanically connected or electrically connected; or connected directly or indirectly through an intermediate, or two elements communicated internally. For a person of ordinary skill in the art, specific meanings of the terms in the present invention should be understood according to specific conditions.

In the description of the specification, the description with reference to terms “an embodiment”, “some embodiments”, “exemplary embodiments”, “an example”, “a specific example” or “some embodiments”, and the like indicate that specific features, structures, materials or characteristics described with reference to the embodiments or examples are included in at least one embodiment or example of the present invention. In the specification, the schematic descriptions of the foregoing terms do not necessarily involve the same embodiments or examples. In addition, the described specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described above, a person of ordinary skill in the art may understand that various changes, modifications, replacements, and variations may be made to these embodiments within the principle and concept of the present invention, and the scope of the present invention is as defined by the appended claims and equivalents thereof 

What is claimed is:
 1. A three-pipe multi-split hot water system, comprising: an outdoor unit (1), the outdoor unit (1) comprising a compressor (11), an oil separator (12), a first switching apparatus (13), a second switching apparatus (14), a fin heat exchanger (15), a double-pipe heat exchanger (16), a compressor heat dissipation module (111), a plate heat exchanger (17), a first electronic expansion valve (101), a second electronic expansion valve (102), a third electronic expansion valve (103), and a gas-liquid separator (18); at least two indoor units (2), any one of the indoor units (2) comprising an indoor unit heat exchanger (21), a fourth electronic expansion valve (22), and an indoor unit fan (23); and; a hydraulic module (3), the hydraulic module (3) comprising a refrigerant-water heat exchanger (31), a water pump (32), a water temperature detection sensor (33), a water flow switch (34), a solenoid valve (35), and a fifth electronic expansion valve (36); wherein the outdoor unit (1) is connected to any one of the indoor units (2) and to the hydraulic module (3) by a gas pipe and a liquid pipe.
 2. The three-pipe multi-split hot water system according to claim 1, wherein a liquid-side cut-off valve (104), a gas-side cut-off valve (105), and a hydraulic module cut-off valve (106) are disposed on the outdoor unit (1), the liquid-side cut-off valve (104) is connected to a liquid pipe of the indoor unit (2) and a liquid pipe of the hydraulic module (3), the gas-side cut-off valve (105) is connected to a gas pipe of the indoor unit (2), and the hydraulic module cut-off valve (106) is connected to a gas pipe of the hydraulic module (3).
 3. The three-pipe multi-split hot water system according to claim 1, wherein the first switching apparatus (13) and the second switching apparatus (14) are four-way valves.
 4. The three-pipe multi-split hot water system according to claim 1, wherein each of the first switching apparatus (13) and the second switching apparatus (14) is provided with an interface A, an interface B, an interface C, and an interface D.
 5. A method for controlling the three-pipe multi-split hot water system according to claim 1, wherein the second switching apparatus (14) and the second electronic expansion valve (102) are controlled to enable the system to implement at least one mode of cooling, heating, hot water production, and defrosting.
 6. The method for controlling the three-pipe multi-split hot water system according to claim 5, wherein when both heating and hot water production are required, the second switching apparatus (14) is powered on, the fin heat exchanger (15) operates as an evaporator, and the second electronic expansion valve (102) is closed.
 7. The method for controlling the three-pipe multi-split hot water system according to claim 5, wherein when heating, hot water production, and defrosting are all required, the second switching apparatus (14) is powered off, and the second electronic expansion valve (102) is opened.
 8. The method for controlling the three-pipe multi-split hot water system according to claim 5, wherein when both cooling and hot water production are required, the fin heat exchanger (15) operates as a condenser, and the second electronic expansion valve (102) is closed.
 9. The method for controlling the three-pipe multi-split hot water system according to claim 5, wherein when both cooling and hot water production with improved heat exchange efficiency are required, the second electronic expansion valve (102) is closed.
 10. The method for controlling the three-pipe multi-split hot water system according to claim 5, wherein when both cooling and hot water production with an increased degree of superheat at light load are required, the fin heat exchanger (15) operates as a condenser, and the second electronic expansion valve (102) is opened. 